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A DYNAMIC SHIFT: A MOLECULAR PERSPECTIVE ON BIDIRECTIONAL HERMPAHRODITISM IN TWO REEF FISH SPECIES IN THE FAMILY GOBIIDAE

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Title:A DYNAMIC SHIFT: A MOLECULAR PERSPECTIVE ON BIDIRECTIONAL HERMPAHRODITISM IN TWO REEF FISH SPECIES IN THE FAMILY GOBIIDAE
Authors:Maxfield, Jessica
Contributors:Cole, Kathleen (advisor)
Zoology (department)
Keywords:Zoology
Evolution & development
Bidirectional sex change
Gobiidae
Hermaphroditism
show 2 moreRNAseq
Transcriptomics
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Date Issued:2019
Publisher:University of Hawai'i at Manoa
Abstract:In the fish family Gobiidae it has been hypothesized that they ability to change sex has evolved independently as many as five times. Two of these proposed events led to protogynous sex change and three of these events to bidirectional sex change. A fish species is described as a bidirectional sex changer when an individual has the ability to go from producing one gamete type to the other and back again as an adult. Changes in gonad morphology as a fish transitions from producing one type of gamete to the other has never been documented in Gobiidae. The genes that regulate the process of transition have also never been explored in a bidirectional sex changing species of fish. Here we document the changes that take place in gonads of two species of bidirectional sex changing goby, Lythrypnus dalli and Eviota epiphanes as they transition from producing one gamete type to the other. These two species represent clades in which it is likely the ability to change sex has evolved independently. We were able group each species into six distinct transitional stages based on the amount of ovarian, testicular, and atretic tissue present in the gonads. With a transitional time series established we then used whole transcriptome sequencing to quantify the genes being expressed over transitional time. We looked at differences in gene expression between all six transitional stages and between ova producing (o-phase) and sperm producing (s-phase) individuals. We found that L. dalli and E. epiphanes use a very different set of genes in order to remodel the gonads during sexual transition. Additionally, there are very few genes known to be important regulators of sexual differentiation/determination in other species of fish that are significantly upregulated and downregulated during the transition process in these two species. With these data we were able to draw conclusions about how differences in morphology may have been correlated to differences in gene expression and add evidence to the hypothesis that this represents two evolutionary events.
Description:Ph.D. Thesis. Ph.D. Thesis. University of Hawaiʻi at Mānoa 2019
Pages/Duration:178 pages
URI:http://hdl.handle.net/10125/63276
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Zoology


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